1. Field of the Invention
This invention relates to a process for the transesterification of fat and oil. More particularly, it relates to a process for the transesterification of fat and oil by using a lipase whereby a transesterified fat and oil of high quality can be readily obtained.
2. Description of the Prior Art
Conventional processes for the transesterification of fats comprise employing various catalysts such as alkali metals and alkali matal alcholates. However none of these processes shows the specificity of the site at which the traansesterification occurs. Thus recently it has been attempted to effect site-specific transesterification by using a lipase.
In order to effect transesterification by using a lipase as a catalyst, it is required to control the moisture content in the reaction system. When the moisture content in the reaction system is too low, the lipase cannot be sufficiently activated and thus the aimed reaction cannot be achieved. When the moisture content is excessively high, on the other hand, the fat is hydrolyzed, which would cause, for example, a decrease in the yield of triglycerides or the deterioration of the obtained transesterified fat. Therefore transesterification with the use of a lipase should be effected under strict control of the moisture content. However water is hardly soluble in substrates or in an organic solvent and the range of the moisture content effective in the reaction is narrow, which makes the control of the moisture content difficult.